Extremely-Low Frequency Electro-Magnetic Radiation (hereinafter referred to as ELF radiation) has been suspected as a possible health hazard involving a wide variety of ills, including immune system injury, cataracts, blurred vision, memory loss, stress, leukemia, interference with the body's natural electro-magnetic fields, abnormal pregnancies, and miscarriages. The ELF radiation that health officials and scientists are most concerned about is in the range of 2 Hz-5 kHz.
ELF radiation is present whenever there are hi-voltage power lines and electric appliances. In computer monitors, magnetic fields guide the electron beams that draw the image on the screen. In the process,-radiation is created that emanates from the neck of the monitor. Travelling in arcs to all sides and to the front of the monitor, this radiation passes completely through the monitor's case and the operator's body.
Common electric appliances such as television sets and hair dryers emit ELF radiation fields. However, exposure to them is usually brief and/or from a distance, entailing low risk. On the other hand, computer monitors often emit ELF radiation as far away as three feet. Computer operators usually sit less than three feet from their computers, entailing substantially greater risk.
Most of the radiation to which one is exposed originates from the neck of the tube and travels in arcs--several feet around and in front of the screen. The deeper the monitor, the stronger the radiation emissions. Relatively very little ELF radiation comes directly from the screen area of a monitor. Thus, all screen-mount filters only afford relatively minimal protection.
Currently available computer monitor ELF radiation shields include external iron-strap shields, internal iron-cylinder shields, coated wire screen filters and coated glass screen filters. Testing of these shields in the 2 Hz to 5 kHz range indicated reductions in the ELF radiation from about 5% to 73%.
Because of the possible health hazards associated with computer monitors, there is the need for improved computer monitor shields that comparatively reduce ELF radiation emissions in view of what is now available.